In response to the demands of consumers who are driven both by ever-escalating fuel prices and the dire consequences of global warming, the automobile industry is slowly starting to embrace the need for ultra-low emission, high efficiency cars. While some within the industry are attempting to achieve these goals by engineering more efficient internal combustion engines, others are incorporating hybrid or all-electric drive trains into their vehicle line-ups. To meet consumer expectations, however, the automobile industry must not only achieve a greener drive train, but must do so while maintaining reasonable levels of performance, range, reliability, safety and cost.
In a conventional vehicle with a large battery pack, such as that typically required for an all-electric or hybrid vehicle with a relatively long electric-only range, the battery pack is normally mounted under the vehicle. This mounting location is generally considered to be optimal, both from a packaging point of view as well as from a vehicle performance point of view in terms of providing a low center of gravity and a desirable weight distribution. Unfortunately due to the thickness of a typical electric vehicle battery pack, mounting the battery pack under the vehicle significantly impacts available passenger space. As illustrated in FIG. 1, these effects are most noticeable in the back seat due to the sloping roofline 101 and the limited leg space in front of the rear seats. In a typical vehicle with an undercarriage mounted battery pack 103, passengers in the rear seats have limited headroom 105. Additionally, due to the raised floor, the passenger's feet are placed higher than desired, causing the passengers to sit with their legs in a semi-raised, awkward position. While it would be possible to alter and raise roofline 101 in order to provide more legroom as well as more headroom 105, except for SUVs and similarly styled vehicles, such a change would generally be aesthetically unpleasing and undesirable. More importantly, the sloping roofline is often required in order to achieve the desired vehicle aerodynamics, an extremely important characteristic for an electric vehicle where increased drag translates directly to lower efficiency and thus the need for a larger battery pack in order to achieve the same vehicle performance.
Accordingly, what is needed is a battery pack system that provides improved seating ergonomics, especially for the occupants of the back seat where legroom and headroom is quite limited. The present invention provides a battery pack design that overcomes the limitations of a conventional battery pack.